Many consumer products contain benefit agents intended for delivery and deposition onto a negatively charged target surface (e.g., fabric, skin, or hair). These products can provide consumer-desired benefits such as softness, hand, anti-wrinkle, hair conditioning, frizz control, skin moisturization, and color protection. Difficulties frequently arise in achieving effective deposition of benefit agents onto these surfaces when the benefit agent is delivered via rinse-off consumer product compositions, especially when those compositions are cleansing products.
Cleansing products such as shampoos, body washes, liquid soaps, and laundry detergents typically contain an excess of anionic surfactant. This makes deposition and retention of hydrophobic benefit agents onto an anionic target surface especially difficult. Various cationic polymers have been proposed as deposition aids for such compositions, but their performance is not always wholly satisfactory. For instance, anionic surfactants can interfere with cationic deposition aid performance by adsorbing onto the deposition aid, as well as by forming complexes that lead to poor shelf stability and loss of cleaning efficacy (e.g., due to flocculation and precipitation). In addition to poor benefit agent delivery, this leads to non-cost-effective use and waste of materials.
Furthermore, while increasing the deposition of the desired benefit agent, deposition aids unfortunately can also increase the deposition of undesired materials such as soil and/or alter the nature of the desired benefit agent. When the deposition aid deposits soil, the whiteness, feel, appearance, and/or cleaning benefits are decreased. When the nature of the desired benefit agent is negatively impacted by the deposition aid, the benefit agent's effectiveness may be decreased and/or the consumer experience arising from the benefit agent's use may be altered in a negative manner.
Deposition aids undergo hydrophobic and/or electrostatic interactions with not only benefit agents, but also other materials, such as soils, to form particulates that have an affinity for consumer relevant substrates such as hair, skin, fabrics, and/or hard surfaces. Such interactions may be particularly pronounced in the presence of surfactants. Thus, there is a need to provide a deposition aid that achieves effective deposition of benefit agents but not of undesired substances.
Many cationic polymers disclosed in the art are not wholly satisfactory for use as deposition aids in consumer product compositions. For example, the material described by Ono (WO 99/32539) comprises end groups having heteroatoms such as oxygen, nitrogen, sulfur, or halogens. These functionalized end groups can lead to undesireable reactions that pose stability issues for compositions comprising these materials. For instance, Ono's silicones can react further through these end groups, leading to further condensation/polymerization of the silicones in the compositions during storage.
Also known in the art are quaternized silicones that include alkylene oxide units, such as U.S. Pat. No. 6,903,061 to Masschelein. The quaternized silicones described by Masschelein tend to be too water soluble, and thus have a reduced capacity as deposition aids, since these materials tend to partition into water at a higher than desired level. Further, when these materials are used as the deposition active, they have an undesirable feel because of their high permeability to water and water vapor. In addition, because of their water solubility, these materials can be difficult to formulate reproducibly. Further, Masschelein discloses materials having only one quaternized nitrogenous group per side of the molecule. This can limit the desired degree of functionality in a silicone material. It would desirable to have a material the provides greater flexibility via the level of quaternization. Similarly, the ethoxylated quaternized silicone materials disclosed by Boutique in U.S. Pat. No. 6,833,344 suffer from many of the same inadequecies of those described by Masschelein.
In an effort to prevent incompatibilities among consumer product composition ingredients, the prior art discloses hydrophobic benefit agents encapsulated within a wall comprising hydrophilic, water-soluble polymers, such as those disclosed in U.S. Pat. Nos. 7,118,057, 7,294,612, and WO 98/11870. The encapsulated benefit agent is mixed into a cleansing/wash-off product composition comprising surfactant. While encapsulation may prevent undesired reactions between ingredients, it can also limit the amount of benefit agent available for surface treatment. Even if the benefit agent capsule adequately deposits onto the substrate, the level of benefit agent available for surface treatment can be limited to that amount which can diffuse through the capsule wall and/or leak due to breakage of the capsule.
Thus there remains a need for additional consumer product cleansing compositions that can adequately deposit hydrophobic benefit agents onto a negatively charged substrate without suffering from the aforementioned deficiencies.